Family violence is on the increase in New Zealand, a report has indicated.

New Zealand Family Violence Clearinghouse, which compiled the report, said it was not clear what was behind the increase.

"We believe that further work is required to understand the causes of this increase," said Clearinghouse researcher Pauline Gulliver.

"Is it also because the police have improved their handling of historic abuse claims? Are advocates in the community providing more support to encourage people to come forward?"

The data collected by government agencies, services and surveys indicate that during 2013:

■ 95,080 family violence investigations were conducted by the police.

■ Offences were recorded at 37,880 of these.

■ 12,490 Police Safety Orders (PSOs) were issued.

■ There were 5025 recorded breaches of Protection Orders and 3835 convictions for Breach of Protection Order and Non-Molestation Order prosecuted.

■ Between 2005 and 2013 the number of sexual offences against adults reported to police increased from 1187 to 1848.

■ The number of reported sexual offences against children increased from 1278 to 2071 in the same period.

Gulliver said that while the number of Police Safety Orders being issued had increased every year since they were introduced in 2010, there had also been a reduction in the number of applications for protection orders.

"If we really want to understand the level of violence that is happening in the community, we need community-based surveys, such as the Violence Against Women survey conducted in 2003," Gulliver said.

The New Zealand Family Violence Clearinghouse is the national centre for collating and disseminating information about domestic and family violence in New Zealand.